I thought I replied to this thread earlier, but maybe I missed a button. Anyway, the project came together well. The speaker works as intended, which is to say that my wife can hear herself practicing now. Thank you all for your help. I couldn't have done it without you.
You guys have inspired me to build an external speaker cabinet as well, so I won't have to deal with space restrictions so much. I'm trying to figure it out, but I can't seem to determine exactly what I'll need. As the previous 2.5w model was discontinued, this is the amp I'm using:
SD-2W Amp Harness
I've been trying to find the right speaker for the application, and the best I've come up with (I'm trying to keep this project cheap) if this one:
JAMO 20307 5-1/2" Treated Paper Cone Woofer
I'd certainly be open to suggestions on speaker choice. That one looked correct to me primarily because of the frequency response, but again, I really don't know what I'm doing. I've been trying to figure out how to determine the size for the enclosure as well, and I'm having trouble. I basically some sort of cubic size measurement, right? Then I can work out the WxDxH more or less however I want? I've tried to find an appropriate calculator online, but haven't been successful. Also, is it reasonable to expect levels around 80db or higher for this project?
Thanks again,
David
You guys have inspired me to build an external speaker cabinet as well, so I won't have to deal with space restrictions so much. I'm trying to figure it out, but I can't seem to determine exactly what I'll need. As the previous 2.5w model was discontinued, this is the amp I'm using:
SD-2W Amp Harness
I've been trying to find the right speaker for the application, and the best I've come up with (I'm trying to keep this project cheap) if this one:
JAMO 20307 5-1/2" Treated Paper Cone Woofer
I'd certainly be open to suggestions on speaker choice. That one looked correct to me primarily because of the frequency response, but again, I really don't know what I'm doing. I've been trying to figure out how to determine the size for the enclosure as well, and I'm having trouble. I basically some sort of cubic size measurement, right? Then I can work out the WxDxH more or less however I want? I've tried to find an appropriate calculator online, but haven't been successful. Also, is it reasonable to expect levels around 80db or higher for this project?
Thanks again,
David
Sorry, you lost me. By "sonic exciter" and "bass shaker," are you referring to the speaker? Let me catch you up. I already installed a 2" full range driver and the mini amp named above into the guitar, and they work fine for quiet practice. The bass now has two outputs: passive and active (using the amp, which works more or less like a pre-amp when used that way) What I'm trying to do now is precisely what digits suggested. I already have the amp in the bass/ I want to be able to run it to a small, lightweight driver in a box.
Thanks for the replies,
David
Thanks for the replies,
David
David,
Presumably the purpose of building an external speaker cabinet is to get deeper bass or more volume or both. That little Jamo is a nice driver for some applications, but offers little more deep bass, and only about the same volume. The player will likely trip over the shoe-box sized enclosure, and the cord will be heavy enough to pull the box around (hmm, could be an interesting advantage!).
For a major step upward in bass depth and volume consider this inexpensive 10-inch driver (10" Ribbed Paper Cone Woofer Speaker) in a closed box of 1 - 2 cf. Stuff with dacron or acoustastuff. Make the box wedge shaped to get the sound up to ear level. Put a strap handle on for easy portability. Construct with 3/8-inch plywood for light weight (yea, the walls will vibrate a little, but that will have minimal negative impact on the sound - could even be a plus). If the specs are at least ballpark, you will get an f3 of 65-53 Hz (1-2cf), and max spl with your 2w amp will be over 90db (nearly 10db higher than the guitar mount and the Jamo).
Good luck,
Bob
Presumably the purpose of building an external speaker cabinet is to get deeper bass or more volume or both. That little Jamo is a nice driver for some applications, but offers little more deep bass, and only about the same volume. The player will likely trip over the shoe-box sized enclosure, and the cord will be heavy enough to pull the box around (hmm, could be an interesting advantage!).
For a major step upward in bass depth and volume consider this inexpensive 10-inch driver (10" Ribbed Paper Cone Woofer Speaker) in a closed box of 1 - 2 cf. Stuff with dacron or acoustastuff. Make the box wedge shaped to get the sound up to ear level. Put a strap handle on for easy portability. Construct with 3/8-inch plywood for light weight (yea, the walls will vibrate a little, but that will have minimal negative impact on the sound - could even be a plus). If the specs are at least ballpark, you will get an f3 of 65-53 Hz (1-2cf), and max spl with your 2w amp will be over 90db (nearly 10db higher than the guitar mount and the Jamo).
Good luck,
Bob
Some bass players are satisfied with response to 2-3kHz, but it's nice to have more extended response and be able to trim back the tone control if thats the desired tone. I suggest using this little Jamo 4 1/2-inch closed back midrange (JAMO 20470 4-1/2" Sealed Back Midrange) and crossing over with a single cap (6.8 uf, 027-336) at about 3kHz.
Bob
Bob
this is very good and cheap Midbass(4 or 8 Ohms), linear response to 5000hz!
Monacor SP60
Monacor SP-60/8 4" Midrange Speaker 60W Max. 8ohm
HIGH-TECH-HIFI
I have them in my Garage, and People ask where is the Subwoofer?! lol
those are little animals! Bestbuy!
Look at this
http://www.bd-design.nl/contents/en-us/d26_Bass_Horn_Design.html
Monacor SP60
Monacor SP-60/8 4" Midrange Speaker 60W Max. 8ohm
HIGH-TECH-HIFI
I have them in my Garage, and People ask where is the Subwoofer?! lol
An externally hosted image should be here but it was not working when we last tested it.
those are little animals! Bestbuy!
Look at this
http://www.bd-design.nl/contents/en-us/d26_Bass_Horn_Design.html
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DYNABLASTERTUNERS - That looks interesting, but I'm not excited about shipping from the UK.
Bob - I understand capacitors from the guitar work I've done, but I'm having trouble figuring out what it means to crossover at 3kHz. Is that an inductor value or something? How would I do what you're talking about? Additionally, if you don't mind another question, regarding the fill material, do I fill up the whole thing or just line the sides? That filler material looks like it could get expensive if I need more than 1 lb. My dimensions as planned are rectangular 24"h x 12"w x 8"d, which according to my calculations makes for something like 1 1/3 cubic feet.
Bob - I understand capacitors from the guitar work I've done, but I'm having trouble figuring out what it means to crossover at 3kHz. Is that an inductor value or something? How would I do what you're talking about? Additionally, if you don't mind another question, regarding the fill material, do I fill up the whole thing or just line the sides? That filler material looks like it could get expensive if I need more than 1 lb. My dimensions as planned are rectangular 24"h x 12"w x 8"d, which according to my calculations makes for something like 1 1/3 cubic feet.
David,
The 10-inch driver is speced as having response that drops off above 3kHz. It undoubtedly becomes gradually directional well below that. The 3khz crossover brings in the midrange gradually (6db/octave) so that it fills in the response where the 10-inch is directional and allows it to essentially take over around 3kHz and above.
The single capacitor starts impeding the signal around 3kHz, gradually choking it off and causing all of it to go through the 10-inch. The response of the 10-inch drops off naturally above 3kHz allowing a more or less smooth transition to the midrange.
Solder either end (it's bipolar so polarity is not an issue) of the cap to the positive lead of the midrange and make the positive connection to the midrange through the cap. Wire the drivers in parallel and in phase - positive to positive and negative to negative.
In order to minimize standing waves in the box, dimensions should not be equal or even close to multiples. For a 1.3 cf box, dimensions should be something like 20x9x12.5 inches.
You will only use around 1/2 to pound of acoustastuff, or 3/4 pounds of dacron. Unless you have an old oillow to scavenge for dacron, the cost of dacron plus gas to go pick it up might get you pretty close to the cost of acoustastuff.
Regards,
Bob
The 10-inch driver is speced as having response that drops off above 3kHz. It undoubtedly becomes gradually directional well below that. The 3khz crossover brings in the midrange gradually (6db/octave) so that it fills in the response where the 10-inch is directional and allows it to essentially take over around 3kHz and above.
The single capacitor starts impeding the signal around 3kHz, gradually choking it off and causing all of it to go through the 10-inch. The response of the 10-inch drops off naturally above 3kHz allowing a more or less smooth transition to the midrange.
Solder either end (it's bipolar so polarity is not an issue) of the cap to the positive lead of the midrange and make the positive connection to the midrange through the cap. Wire the drivers in parallel and in phase - positive to positive and negative to negative.
In order to minimize standing waves in the box, dimensions should not be equal or even close to multiples. For a 1.3 cf box, dimensions should be something like 20x9x12.5 inches.
You will only use around 1/2 to pound of acoustastuff, or 3/4 pounds of dacron. Unless you have an old oillow to scavenge for dacron, the cost of dacron plus gas to go pick it up might get you pretty close to the cost of acoustastuff.
Regards,
Bob
No, I wasn't referring to the speaker. I was replying to oublie's suggestion. Google "bass shaker" (with the quotes around the words) if you want to see what we were referring to.
Just carry on as you are doing. I second the recommendation that the external box speaker be at least 8 or 10 inch. I would suggest a driver intended for guitar or professional use rather than a car / home hifi speaker - They are usually more efficient and have a more extended frequency response, which may save you the complexity of adding a midrange speaker and capacitor etc. If I were intending to build such a thing, I would probably choose a driver from the Eminent range. Other people will probably have additional suggestions.
Thanks Bob. I understand now. I thought you needed a resistor and a capacitor to make that happen, but your way is much easier.
Don - Ok, I get what you were talking about. I see why oublie suggested it too. Most likely I'm gonna go with the two speakers Bob suggested, and build it just as he's recommended, though I may modify the box dimensions a little, making sure to avoid multiples. Thanks for your recommendations.
Don - Ok, I get what you were talking about. I see why oublie suggested it too. Most likely I'm gonna go with the two speakers Bob suggested, and build it just as he's recommended, though I may modify the box dimensions a little, making sure to avoid multiples. Thanks for your recommendations.
"I would suggest a driver intended for guitar or professional use rather than a car / home hifi speaker - They are usually more efficient and have a more extended frequency response, which may save you the complexity of adding a midrange speaker and capacitor etc. If I were intending to build such a thing, I would probably choose a driver from the Eminent range."
Don,
I generally agree, but within solidfooting's apparent budget, and given the fact that the amplifier is a 2W chip, the recommended drivers should perform quite well. They will probably do well up to about 25w in this application.
The Eminence Alpha 10a (at $45, the lowest priced appropriate Em driver) will handle 150w, is likely 2-4 db more efficient, will give an f3 of 63Hz in a 1.5cf BR, and has a 'usable' response to 4.5kHz. It's a nice driver and would make a good bass practice amp with a 40-60w chip amp (but that's another project!).
The 2 Peavey 8-inch guitar speakers currently on sale at PE have a high Fs and high Qts suitable for typical guitar amp open back use.
Regards,
Bob
Don,
I generally agree, but within solidfooting's apparent budget, and given the fact that the amplifier is a 2W chip, the recommended drivers should perform quite well. They will probably do well up to about 25w in this application.
The Eminence Alpha 10a (at $45, the lowest priced appropriate Em driver) will handle 150w, is likely 2-4 db more efficient, will give an f3 of 63Hz in a 1.5cf BR, and has a 'usable' response to 4.5kHz. It's a nice driver and would make a good bass practice amp with a 40-60w chip amp (but that's another project!).
The 2 Peavey 8-inch guitar speakers currently on sale at PE have a high Fs and high Qts suitable for typical guitar amp open back use.
Regards,
Bob
He said Eminent. I wondered if he meant Eminence. I'm very familiar with those, and what you say is exactly right. Great speakers, but out of the price range for this project. Maybe someday if I build an amp for myself.
I drew up something rough to help me visualize dimensions. This is not to scale. Realizing how much space those drivers will take up, I think a wedge might be best after all. The following dimensions yield a volume of 2,156 cubic inches, or about 1 1/4 cubic feet, per my math. I tried to stay away from too many multiples, on your advice. What do you think?
Thanks,
David
I drew up something rough to help me visualize dimensions. This is not to scale. Realizing how much space those drivers will take up, I think a wedge might be best after all. The following dimensions yield a volume of 2,156 cubic inches, or about 1 1/4 cubic feet, per my math. I tried to stay away from too many multiples, on your advice. What do you think?
Thanks,
David
"Following are the proposed dimensions. It's 1,902 cubic inches, or 1.1 cubic feet."
David,
That should work just fine. You have the right idea about the box dimensions and volume. No even multiples and volume between 1 to 2 cf, with bigger going a little lower.
With acoustastuff or dacron, you will have to tease it out a little to get rid of dense (and wasteful) knots and produce a more uniform and open damping material.
Should be a nice project. Let us know how it turns out.
Bob
David,
That should work just fine. You have the right idea about the box dimensions and volume. No even multiples and volume between 1 to 2 cf, with bigger going a little lower.
With acoustastuff or dacron, you will have to tease it out a little to get rid of dense (and wasteful) knots and produce a more uniform and open damping material.
Should be a nice project. Let us know how it turns out.
Bob
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